Model comparison of Lambda CDM vs R_h=ct using cosmic chronometers

Abstract

In 2012, Bilicki and Seikel (Mon Not R Astron Soc 425:1664, 2012) showed that H(z) data reconstructed using Gaussian Process Regression from cosmic chronometers and baryon acoustic oscillations, conclusively rules out the R_h=ct model. These results were disputed by Melia and collaborators in two different works (Melia and Maier in Mon Not R Astron Soc 432:2669, 2013; Melia and Yennapureddy in JCAP 2018:034, 2018), who showed using both an unbinned analysis and Gaussian Process reconstructed H(z) data from chronometers, that R_h=ct is favored over Lambda CDM model. To resolve this imbroglio, we carry out model comparison of Lambda CDM versus R_h=ct by independently reproducing the above claims using the latest chronometer data. We perform model selection between these two models using Bayesian model comparison. We find that no one model between Lambda CDM and R_h=ct is decisively favored when uniform priors on Lambda CDM parameters are used. However, if we use priors centered around the Planck best-fit values, then Lambda CDM is very strongly preferred over R_h=ct.